Functional Significance of Cytochrome P450 1A2 Allelic Variants, P450 1A2*8, *15, and *16 (R456H, P42R, and R377Q).
10.4062/biomolther.2015.009
- Author:
Young Ran LIM
1
;
In Hyeok KIM
;
Songhee HAN
;
Hyoung Goo PARK
;
Mi Jung KO
;
Young Jin CHUN
;
Chul Ho YUN
;
Donghak KIM
Author Information
1. Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea. donghak@konkuk.ac.kr
- Publication Type:Original Article
- Keywords:
P450 1A2;
Allelic variants;
Polymorphism;
Methoxyresorufin;
Phenacetin
- MeSH:
Biotransformation;
Blotting, Western;
Cytochrome P-450 CYP1A2*;
Escherichia coli;
Genetic Variation;
Metabolism;
Phenacetin;
Polymorphism, Single Nucleotide
- From:Biomolecules & Therapeutics
2015;23(2):189-194
- CountryRepublic of Korea
- Language:English
-
Abstract:
P450 1A2 is responsible for the metabolism of clinically important drugs and the metabolic activation of environmental chemicals. Genetic variations of P450 1A2 can influence its ability to perform these functions, and thus, this study aimed to characterize the functional significance of three P450 1A2 allelic variants containing nonsynonymous single nucleotide polymorphisms (P450 1A2*8, R456H; *15, P42R; *16, R377Q). Variants containing these SNPs were constructed and the recombinant enzymes were expressed and purified in Escherichia coli. Only the P42R variant displayed the typical CO-binding spectrum indicating a P450 holoenzyme with an expression level of approximately 170 nmol per liter culture, but no P450 spectra were observed for the two other variants. Western blot analysis revealed that the level of expression for the P42R variant was lower than that of the wild type, however the expression of variants R456H and R377Q was not detected. Enzyme kinetic analyses indicated that the P42R mutation in P450 1A2 resulted in significant changes in catalytic activities. The P42R variant displayed an increased catalytic turnover numbers (k(cat)) in both of methoxyresorufin O-demethylation and phenacetin O-deethylation. In the case of phenacetin O-deethylation analysis, the overall catalytic efficiency (k(cat)/K(m)) increased up to 2.5 fold with a slight increase of its K(m) value. This study indicated that the substitution P42R in the N-terminal proline-rich region of P450 contributed to the improvement of catalytic activity albeit the reduction of P450 structural stability or the decrease of substrate affinity. Characterization of these polymorphisms should be carefully examined in terms of the metabolism of many clinical drugs and environmental chemicals.
